//Java Crux in Challange-Arrays section
//Form biggest no.
import java.util.*;
public class Main {
public static void main(String args[]) {
Scanner sc = new Scanner (System.in);
int tc=sc.nextInt();
int[] arr= null;
String ab ="";
String ba="";
String ans ="";
for(int row=1;row<=tc;row++) {
int nv=sc.nextInt();
arr =new int[nv];
for(int col=0;col<nv;col++) {
arr[col]=sc.nextInt();
}
for(int i=0;i<nv-1;i++) {
for(int col=i+1;col<nv;col++) {
ab=(String.valueOf(arr[i])+String.valueOf(arr[col]));
ba=(String.valueOf(arr[col])+String.valueOf(arr[i]));
if(Integer.valueOf(ab)>Integer.valueOf(ba)) {
col=col+1-1;
}else {
int temp=arr[col];
arr[col]=arr[i];
arr[i]=temp;
}
}
}
for(int i=0;i<arr.length;i++) {
ans+=String.valueOf(arr[i]);
}
System.out.println(ans);
}
}
}